"The broad, long-term objective of this project is to contribute to the understanding of human pattern vision." The experiments and modeling presented here are specifically concerned with the detection and appearance (specifically the apparent contrast) of periodic (grating/Gabor) stimuli in various contexts. The term "context" is used to refer to the various backgrounds/pedestals/surrounds/etc that can be used to influence the appearance and detectability of stimuli. The PI has spent many years developing a model to account for some the phenomena under study here. In the present research plan, he proposes to collect a body of data that will allow him to modify and/or extend this model.